Technical Field
The present invention relates to a process for synthesizing ester compounds (via alkoxycarbonylation reactions) and a process for synthesizing amide compounds (via aminocarbonylation reactions) in the presence of a solid-supported palladium catalyst.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Palladium catalyzed carbonylation reactions of aryl halides (carbonylative coupling) in the presence of alcohol or amine nucleophiles represent major industrial processes for the production of value-added bulk and fine chemicals. It is a versatile synthetic pathway which allows the obtaining of a wide range of linear, branched and cyclic carboxylic acids and their derivatives in one step and from easily accessible starting precursors [El Ali, B. and Alper, H. Transition metals for organic synthesis: Building blocks and fine chemicals (eds. M. Beller and C. Bolm); Wiley-VCH verlage GMBH, 2004 weinheim, Germany; Jayasree, S.; Seayad, A.; Gupte, S. P.; Chaudhari, R. V. Catalysis Letters, 1999, 5, 8213; Scrivanti, A.; Matteoli, U.; Beghetto, V.; Antonaroli, S.; Scarpelli, R.; Crociani, B. J. Mol. Catal. A: Chem. 2001, 170, 51; El Ali, B.; Alper, H.; in: M. Beller, C. Bolm (Eds.), Transition Metals for Organic Synthesis, Vol. 1, VCH, Weinheim, 1998, 57]. The products of alkoxycarbonylation and aminocarbonylation reactions are extensively used as building blocks for various materials ranging from polymers [Claufield, M. J.; Qiao, G. G.; Solomon, D. H. Chem. Rev. 2002, 102, 3067], light sensitive and electrically conductive materials, detergents, flavors, fragrances and various pharmaceuticals [T. W. Graham Solomons, Organic Chemistry, 11th Edition, Wiley, 2013; C. Liana Allen, Catalytic Approaches to the Synthesis of Amide Bonds, PhD Thesis, University of Bath, 2012; David Rowe, Chemistry and Technology of Flavours and Fragrances, Wiley-Blackwell, 2009; Bianchini, C.; Mantovani, G.; Meli, A.; Oberhauser, W.; Bruggeller, P. and Stampfi, T. J. Chem. Soc., Dalton Trans., 2001, 690].
A plethora of homogeneous palladium catalysts have been described to successfully catalyze carbonylative coupling reactions with high selectivity, activity and low catalyst loading [Fang, W.; Deng, Q.; Xu, M.; Tu, T., Org. Lett., 2013, 15, 3678-3681; Nielsen, D. U.; Taaning, R. H.; Lindhardt, A. T.; Gøgsig, T. M.; Skrydstrup, T., Org. Lett., 2011, 13, 4454-4457; Tambade, P. J.; Patil, Y. P.; Bhanushali, M. J.; Bhanage, B. M., Synthesis, 2008, 2347-2352; McNulty, J.; Nair, J. J.; Robertson, A.; Lei, A., Org. Lett., 2007, 9, 4575-4578]. However, the complete removal of the homogeneous catalyst from the cross coupling products is a tedious and costly process. This reduces the chances of industrial implementation of most homogeneous palladium catalysts since metal contamination in the final products is highly regulated by the industries [Polshettiwar, V.; Len, C.; Fihri, A. Coord. Chem. Rev. 2009, 253, 2599].
A suitable method for overcoming the separation problem is by immobilizing the homogeneous catalyst on a solid support [Gruber-Woelfler, H.; Radaschitz, P. F.; Feenstra, P. W.; Haas, W.; Khinas, J. G. J. Catal. 2012, 286, 30]. Other than easy removal from the coupling products, the immobilized catalyst can be also effectively recycled and re-used [Hallamn, K.; Moberg, C. Tetrahedron: Asymmetry, 2001, 12, 1475]. The ability to separate and reuse the supported catalyst makes it more viable alternative especially from economical point of view. Taking into consideration the substantial advantages of supported catalysts over the homogeneous catalysts, the interest towards the immobilization of palladium catalysts has been increasing rapidly [Lei, Y.; Wu, L.; Zhang, X.; Mei, H.; Yanlong Gu, Y.; Li; G., J. Mol. Catal., 2015, 398, 164-169; Mane, R. S.; Sasaki, T.; Bhanage, B. M., RSC Adv., 2015, 5, 94776-94785; Beletskaya, I. P.; Ganina, O. G.; Reac. Kinet. Mech. Cat., 2010, 99, 1-4; Khedkar, M. V; Sasaki, T.; Bhanage, B. M., ACS Catal., 2013, 3, 287-293; Dang, T. T.; Zhu, Y.; Ngiam, J. S. Y.; Ghosh, S. C.; Chen, Seayad, A. M. ACS Catal., 2013, 3, 1406-1410]. Although several supported palladium catalysts have been reported, the application of supported palladium-bis(oxazolines) catalysts in carbonylative coupling reactions has never been explored [Ibrahim, M. B.; El Ali, B.; Fettouhi, M.; Ouahab, L. Appl. Organometal. Chem, 2015, 29, 400.; Ibrahim, M. B.; Hussain, S. M.; Fazal, A.; Fettouhi, M.; El Ali, B. J. Coord. Chem. 2015, 68:3, 432; Hussein, S. M.; Ibrahim, M. B.; Fazal, A.; Suleiman, R.; Fettouhi, M.; El Ali, B. Polyhedron, 2014, 70, 39]. Therefore, the process of synthesizing ester and amide compounds via alkoxycarbonylation and aminocarbonylation reactions of aryl halides is discussed, wherein a palladium-bis(oxazoline) complex supported on Merrifield's resin is used as a reaction catalyst. Further, the catalytic activity and recycling ability of the catalyst in alkoxycarbonylation and aminocarbonylation reactions of aryl halides have been studied.
In view of the forgoing, one objective of the present invention is a process for synthesizing ester compounds (via alkoxycarbonylation reactions) and a process for synthesizing amide compounds (via aminocarbonylation reactions) in the presence of a solid-supported palladium catalyst.